Liquid-dispensing system with remote control



May 29, 1956 J. A. WOOLDRIDGE LTQUTO-OISPENSING SYSTEM WITH REMOTECONTROL 2 Sheets-Sheet Filed July 22, 1952 May 29, 1956 J. A. WOOLDRIDGE2,747,598

LIQUID-DISPENSTNG SYSTEM WITH REMOTE CONTROL Filed July 22, 1952 2sheets-snaai 2 Fig. 3

atent 2,747,598 Patented May 29, 1956 LIQUID-DISPENSIN G SYSTEM WTHREMOTE CNTRL James Arthur Wooldridge, Great St. Helens, London, England,assignerV to Shell Development Company, Emeryville, Calif., acorporation of Delaware Application July 22, 1952, Serial No. 300,183

Claims priority, application Great Britain July 31, 1951 19 Claims. (Cl.137-193) This invention relates to Vliquid-dispensing systems of thekind in which a pump delivers liquid into a line having-a delivery valveat one or more dispensing points remote from the pump. The invention isespecially applicable to the so-called static systems for fuellingaircraft, in which fuel is fed by a pump from a static bulk storage tankthrough a permanent system of pipes to a number of dispensing stationslocated adjacent the parking positions of the Vaircraft and equippedwithl dispensing devices. The dispensing devices, each of which iscontrolled by a delivery valve, are'generally remote from the bullistorage tank and the pump, the latter usually being situated adjacentthe tank.

The discharge of fuel at the dispensing stations is necessarilyintermittent, and at the less `busy aerodromes there are frequentperiods when the delivery valve or valves are closed. Unless an operatoris stationed `at the pump house to start and stop the pump as required,the pump operates for substantial periods of time against the pressureexerted by the usual relief or by-pass valve with whichV such pumps areprovided, with the result that unnecessary power consumption andwear'and tear take place. W'hilst an electrically driven pump could becontrolled by the operator at the dispensing station, this woudnecessitate the provision of a control circuit to each trol rack andstarter motor of the engine, but again the necessary control circuitmust be extended to each dispensing station. A further and more seriousdiiculty in the case of a diesel engine, especially where tracconditions on the aerodrome are such that the engine would be startedand stopped frequently, is the wear and tear on the engine associatedwith such starting and stopping.

An object of the present invention'is to provide a system whereby theload on the pump is reduced automatically, whenever the delivery valveor allv ofvthem is or are closed, to a valueV substantiallybelow thatallowed by the relief or by-pass valves hitherto provided and withoutthe necessity for stopping the prime moverwhich drives the pump.

According to the present invention a liquid-dispensingV system includesa pump, a delivery line connecting thedischarge side of said pump to atleast one dispensing devicev controlled by a delivery valve, anon-return valve in said delivery line, said non-return valve permittingliquid 'flow from said pump to the dispensinggdevice or devices but notviceversa, vand a by-pass line providing 'a path between the dischargeand suction sides of said Y pump through a by-pass valve which isoperative to vary the resistance to liquid flow offered by said by-passline delivery valve or valves and to afford a low-resistance by-pass toYsaid pump when -the pressure at said point in the v'deli-verylinereaches'a predetermined value.i

Preferably the system also includes a pressure-storage vesselcommunicating with said delivery line at a point" between saidnon-return valve and the delivery valve orV valves.

The by-pass valve preferably includes a main valve member, the positionof which determines the resistance' to liquid flow oifered by theby-pass line, and a pilot valve acted upon by the pressure at Said pointin the delivery line between the non-return valve and the delivery'valveor valves, which pressure tends progressively to open' said pilot valveagainst aV force biasing said pilot valve` to the closed position tovary the position of said main' valve member, the disposition of saidmain valveY mem:v ber being such as to close said by-pass line whensaidnpilot valve is closed.

The pilot valve preferably functions in such a man;` i

ner as to cause the main valve member progressively/'td reduce theresistance to liquid flow Voffered by the by-passl line until thepressure at said point in the delivery line reaches a predeterminedvalue above which said pilot4` valve causes said main valve member toopen fully" to provide a low-resistance by-pass to the pump. v

The main valve member may serve in its closed position to separate twoportions of a chamber housing said'A main valve member, in one of whichportions operates a". piston connected to and of larger surface areathan said` main valve member, means being provided whereby; on Aoperation of the pilot valve, the liquid pressure acting on the side ofthe piston adjacent the main valve :meme ber is progressivelytransmitted so as to act on both sides ofv saidpistonl to open said mainvalve member, andk whereby on closure `of said pilot valve the liquidpressure on the piston face remote from the main valve mem-*- ber isbled away to close said main valve member.

Advantageously the arrangement is such that the pilotv valve when fullyopened is caused to move to the closed position only when the pressureat said point in the delivery line falls to a value below thatcausingwinitialf opening thereof.

Conveniently, the delivery line is provided with a ven-V turiconstriction at the said point between the non-gi return valveand thedelivery valve or vales at which'V the pressure is determined and theby-pass valve is ar-V ranged to open fully only when liquid ow throughtheventuri constriction is substantially zero.

A static fuelling system for aircraft in accordance with.y the inventionwill now be described by way of example and with reference to theaccompanying drawings ,forni-t. ing a part of this specification, inwhich:

Figure 'l is a diagrammatic general arrangement view of a dispensingsystem according to the invention; l

Figure 2 Yis an elevation view of a part of the dispensing system,namely that pertaining to the pump,i

- and its by-pass valve, parts being shown diagrammati-V cally; and

Figure 3 is a detailed sectional view of the by-pass valve.

Referring first to Figure l, the complete system inf. cludes thefollowing principal elements:` a source Y of v liquid, such as a bullistorage 'tank or reservoir 6 from which liquid flows to a supply pipe iwhich mayhave a shut-ofvalve a pump 9 having the suction thereof^`connected to the supply pipe 7 and drivenby any suitable l motor 10,such as a diesel engine which may be'provided with the usual governorfor controlling the supply of fuel v theretoin accordance with the load;a by-pass line hav` ing serially connected parts lfm, 1lb,interconnecting e the suction and pressure discharge sides of the pump;a ow control valve l2 in the by-pass line; a pressure` delivery pipeline i3 having a check or non-return valve 14 disposed to permit ow onlyaway from the pump;'.one

or more dispensing outlets 15, a, etc., which may be located at dilerentdispensing stations of the aireld or other dispensing installation, forexample in pits as shown, and which are connected to the deliverypipepline by suitable branches thereof, each dispensing outlet includingat least a delivery shut-off valve 16, 16a, etc., and, if desired,either a coupling device 17, 17a, etc., for attaching a hose 18 fittedwith a suitable nozzle 19Y for attachment to the fuel tank of anaircraft, or merely a permanently attached hose; and a.pressure-responsive actuating device for operating the flow controlvalve 12 in the by-pass line in accordance with the pressure in thedelivery pipe line downstream of the check valve 14, said actuatingdevice including a valve actuator 20 and a pressure-responsive element,which may be simply a tap 21 in communication with the interior of thepipe line 13,-and further connected to the actuator 243 by anysuitable'device for transmitting a signal corresponding to theprevailing pressure, represented diagrammatically as a transmission line22, it being understood that the latter may be merely an electricalcable. ln its broadest aspect, the element 21 is any device for sensingthe pressure in the pipe line 13 and the line 22 is any hydraulic,pneumatic, electrical, etc., device for transmitting the sensing;however, as will be explained in detail in connection with the specificembodiment of Figs. 2 and 3, it is preferred to have this elementrespond not only to the static pressure but also to the velocity ofliquid ow in the line 13, to indicate a lower pressure upon an increaseof iiow. The actuator 20 is arranged to open the valve 12 eitherprogressively or completely'upon a rise in the indicated pressure abovea predetermined value and to close the valve upon a fall in pressure,and the valve 12 is preferably of the type offering as low a owresistance as practicable to the passage of liquid when fully open.Preferably, although optionally, the delivery pipe line 13 is providedat a point therein downstream of the check valve 14 with apressure-storage vessel or reservoir 23 of any suitable type, such asone containing a compressed gas in direct contact with the liquid orisolated therefrom by a diaphragm, a gas bag, etc., as are well known inthe art.

In operation, the pump 9 is normally kept in operation continuouslywhile the airport is in condition to dispense liquid fuel. When any ofthe delivery valves 16, 16a, etc., is open, the liquid pressure in thepipe line 13 falls and the signalled or transmitted pressure of thetransmission line 22 becomes sufficiently low to cause the actua-V tor20 to shut the main valve 12 in the by-pass line. The pump 9 is therebyenabled to force liquid fuel from the supply pipe 7 to the delivery pipeline 13 through the check valve 14, which is of the type offering aminimum of resistance. When all of the delivery valves 16, 16a, etc.,are shut the pressure in the delivery pipe line rises, resulting in anincreased higher signalled or transmitted pressure which causes theV'actuator 20 to open the valve 12; this decreases the pressure on thepressure discharge side of the pump, but the check valve 14 preventsback- Vilow of liquid fuel and maintains the pressure in the pipe line13 at the increased value. The pump is thereby enabled to pump liquidthrough the by-pass line 11a, 11b, against a negligible pressure head.Hence it becomes unnecessary to shut down the pump 9 and the motor 10even though a positive displacement pump, such as a reciprocating pistonpump or a rotary pump, is used, and thesystem can be left ready forinstant operation should one or more of the delivery valves 16, 16a,etc., be opened. It should be understood, however, that the system mayalso be employed with centrifugal pumps. When any of the delivery valvesis opened the pressure in the delivery pipe line falls, causing theactuator to shut the valve 12 and restoring the system to the conditionrst described. The usual governor on the motor 10 regulates the supplyof energy to it to maintain the pump'speed more or less constant, e. g.,in the case of a diesel engine, by decreasing the amount of fuelsupplied when the shaft speed increases due to decreased loadV when theby-pass valve 12 is opened; hence but little power is consumed when noliquid fuel is dispensed. It is evident that such a system is wellsuited to use particularly at airelds where fuelling operations occuronly occasionally but are yet of suicient frequency to make itinadvisable to start and stop the diesel or other engine ltles the valve12 to varying degrees.

which operates the pump every time it is desired to fuel an aircraft.

As will be explained Vin detail below, the actuator 2l) need not be onewhich causes only complete opening or closing of the valve 12; it may beof the type that throt The latter is useful when, for example, severaldispensing stations are provided; it then becomes desirable to shut thevalve 12 completely only when liquid is being dispensed at a high rate(as when several dispensing devices are in use) Vand to shut the valvepartially when liquid is being dispensed at a low rate.

The pressure reservoir 23 smooths out minor pressurefluctuations in thepipe 13. lts main function is to maintains a pressure within thedelivery pipe line 13 for moderately extended periods despite a slowleakage of liquid from the pipe line, thereby preventing rapidlyrecurring operation of the valve 12. Rapidly recurring operation of thevalve or chattering is further avoided by arranging the actuator 20 toopen the valve 12 at a higher transmitted pressure than that at Vwhichthe valve is closed, and such an arrangement is facilitated by the useof the reservoir 23.

The invention will be further described' with reference to a specificembodiment, which is illustrative of the diagrammatic showing of Figurel. Referring to Figure 2, the pump has the suction side 24 thereofconnected to thc supply pipe 7 and to the branch 11b of the'by-passYline. The pressure discharge side 25 of the pump is connected to thebranch 11a of the by-pass line and to the nonreturn valve 14, thedownstream end of the latter being connected to the delivery pipe line13 through branched conduits 26 and 27 which collectively form a part ofthe pressure sensing element 21 of Figure 1. The valve 14'is of a typeaifording only a small resistance to the ilow of liquid in the directionof the dispensing points. The branch 26 may contain a normally-closed,spring-loaded valve 28 for diverting ow through the branch 27, therebyinsuring that liquid iiow to the dispensing devices is alwaysaccompanied by liquid flow through the branch 27, even at low rates ofilow. The spring of the valve 28 is weak enough to permit the valve tobe opened by the pressure of the liquid when large rates of flow occur.The branch 27 contains a venturi constriction 29 having a port 3@connected to one end of the transmission line 22, which is in this casea bleed line and may have a small bore. The other end of the line 22 isconnected to the valve acuator 29 which actuates the valve 12 in theby-pass line 11a, 11b. Connected to the delivery pipe line 13 at a pointdownstream of the spring-loaded valve 28 is the pressure-storagereservoir 23, which may conveniently be an air-expansion chamber, whichfunctions to eliminate or reduce pressure uctuations which atect theoperation of the actuator 20 and by-pass valve 12, such fluctuationsbeing, for example, the effect of leakage which may occur in thedelivery pipe line or in the dispensing system on shut down.

The by-pass valve 12 and actuator 20 are shown in detail in JFigure 3.They are Varranged lin a casing 31 provided with two cylindrical bores32 and S3 of which the plates 32a and 32b, is divided by an aperturedpartition 36 carrying a ring 37 which has a press t withthe partition..

averses 36;"it 'is shaped to provide -a'valve oriiceconstitutingaseating for the valve member 34. The valve member 34 tion sides of thepump 9 through large por-ts' iii-'and 41,

respectively, of which port 40 is situated on the piston side of thevalve member 34 and port 41 is situated on the opposite side thereof,The maximum opening of the main valve member 34 is limited by a hollowstop or projection 42formed on the end plate 32a and having a main-bore43"and a vertical bore 43a set back from the open end thereof.' Thevalve member 34 is guided in its movement towards and away from thevalve orice by means comprising an open cylindrical framework-44 carriedby the rod 38 'and slidably engaging the cylindrical part of the oriceinthe ring 37, A lowconnection is provided between that part or thechamber 32 on the inside of the piston 39` (to the right in Fig. 3) andthat on-the outer face of the valve member 34, i. e., that incommunication through the port 41 with the suction side 24 of the pump,to enable pressure in the space conned by the piston 39 to bleed away tosuction, the' said connection comprising a n'e bore 45 extending axiallythrough the piston 39, the piston rod 3S and the valve member 34. Theeiective sizeof the bore 45 is determined by a removable, apertured plug45 that is rotatably mounted in the main valve member 34, and can Abeadjusted to restrict the-size of thepassageway through the main valvemember at will to" vary the rate at which the pressure can bleed away.Moreover, the vertical bore 43a in the stop 42 linsures thatcommunication between the bore 45 and suction from the port 41 ismaintained when the valve member 34' lies fully open against the stop42.

The pilotvalve chamber 33 is closed at -one end by a plug 47 having abore 48 providing Vconnection with the end of the bleed line 22;.theother end of the chamber around .which lis disposed a compression spring57i-for biasing the pilot valve to the biased position shown. rlie end52 of this portion 50 constitutes a stop for limiting-the movement ofthepilot valve member 35' in the chamber 33'. The end of the pilot valvechamber 33' remote from the compression spring 51' is enlarged in twosteps to form two'adjoining portions 53 and 54, the latter of whichreceivesfV the plug 47`and is closed thereby. he ping 47 carries acollar 55, threadedly connected for-retaining the end of the bleed line.22 which has an enlargement 55 with a frusto-conical tace for sealingcontact with the plug 47. Theaxial Vbore 48'i'n the plug 47 has anenlarged portion 57iwhich` opens into the pilot valve chamber 33 andpro-- vides communication'betv/een the latter and the bleed line 221';Slidablydisposed within, and extending the greater part of the lengthof, the chamber 33'is the elongated -pilotvalve member 35 comprising acentral stem portionV 53 of smaller'diameterthan the bore-of the chamber33, which stem portionis enlarged at its ends to form cylindricalportions 59'and i'which slidably engage the inner wall of the chamber33.

The end portion 59. of the pilot valve member'35 is counterboredY andthe hollow end-thereofenclo'ses part:

of the compression spring 51, whilst the other end portion` S0-'carriesa shortA cylindrical extension 61 of smaller diameter. The extension 61has a slidingY iitin the enlarged bore portion 57 and is of sufficientlengthv to remain-in sliding engagement therewith both in the-closed andpartly` open positions of the valve member 35, but which is carriedclear of the plug 47 at the fully open position of the' valve member.`The stem portion 58 of the valve member tapers outwardly at 62 to the'full diameter ofthe hollow end portion .S9-thereof for 'a purposehereinafter 'explained;l

Ports 63,5 64'" and 65 are providedbetween *theV main valve chamber 32and the pilot valve' chamber`33jof' which port 63 provides communicationbetween the part of the chamber 33 conned between the end 59 of thepilot' valve 35 and the plug 49, and the part of the chamber 32 in the.suction side of the valve 34, and port 65 provides com# municationbetween the part of the control valvechamber 33 containing the centralvalve stem 53 and the space i on'the inner side of the piston 39; bothremain open forV all positions of the pilot valve 35. Port 64, whichcom-v municates at one end with the pressure side of the main valve 34and at the other end with an intermediate point of the chamber 33, isnormally closed'by the enlarged en'd portion59 of the valve member andis opened progressively by movement of the valve member 35 vagainstthespring 51.

The enlarged portion 53 of the chamber 33 is in communication with thatpart of the chamber 33 which'is confined between the end 59 of the pilotvalve member and the plug 49 by way of a circumferential channel 66:

and radial bores 67 in the end portion 6i? and an axial bore 68 in thestern 58.

The system operates as follows:

When the shut-off valve 8 is open and liquid is owingfrom the source'through the supply pipe 7, pump 9' and delivery pipe line 13 to thedispensing outlets 15, 15a,V etc., pilot valve member 35 is in itsbiased or closed posi-.- tion as shown in'Figure 3. This occurs becauseall-or. part of the liquid ows through the venturi constructionv 29`dueto the action of the valve 255, causing suchfareduction in the pressureof the liquid in the bleed line 22 lthat the force exerted by the spring51-overcomes the pressure exerted by that liquid on the .face A- of the.

pilot valve 35, this face being a movable wall for the.

With the pilot valve member 35 the area of the latter is greatery thanthat of the facev B of the valve member 34 there is a pressure diierencewhich holds the valve member 34 closed against its seat#- ing 37,'asshown in the drawing.

When 'the rate of liquid How to the dispensing outlets decreases as theresult of closing one or more,- lessthan-l all, of the-delivery valves16,16@ etc., the rate ofliquidow through the venturi 2,9 decreases andthe liquid pressure inthe bleed line22 Vaccordingly rises with a corre`-sponding increase in the pressure acting on the Yface VA of'fthe pilotvalve member 35. As a resultv the valve member 35 overcomes the forceexerted by the spring 51.'

opening of the port 64, with consequent gradual build 'up of pressure onthe inner face D of the piston 39. This partial movement of the pilotvalve stops when the spring 51 is compressed sufficiently to overcomethe increasedV force of the huid acting on the face A. The stiffness ofthe spring is such that, with at least partial liquid owcontinuingthrough Vthe venturi constriction, the' pilot valve cornes to rest atanintermediate, partly openposition, withl the extension 61 still withinthe bore 57. Liquidl thus enters the right end of the chamber 32 throughthe' port `65 at a restricted Vrate and simultaneously bleeds oitthrough the bore 45. The extent to which the pressure is built up on thefaceD is, therefore, dependent upon the extent to which the tapered`part 62"'uncovers the port 64.V The effect of this increase in.pressure on face D is hnally to remove thepressure difference holding'the main valve member 34 closed, whereupon the Vmain valve'opens to anextent proportional to the pressure in the' delivery line 13 'toprovidev an 'alternativeoutletfor" the' liquid 'discharged by the pump9.F In Wytle" animos f 7 valve member 34 functions in a manner similarto that of the known pump relief valves.

As soon as the rate of liquid flow through the venturi 29 increasesagain as the result of an increased take off from the dispensingoutlets, the pressure of the liquid in the bleed line 22 decreasescorrespondingly and the resulting reduction in the force acting on theface A of the pilot valve member 35 allows the valve 35 to move back toits rest position under the action of the spring 51. Communicationbetween the discharge side 25 of the pump 9 and the inner side of thepiston 39 through ports 64 and 65 is thereby cut off and the pressureacting on the face D of the piston 39 decreases by bleeding to suctionthrough the bore 45 in the piston rod 3S; the valve 34 therefore closesagain as soon as the pressure difference on the adjacent sides of thevalve member 34 and the piston 39 due to the difference in their surfaceareas is re-established.

When all the delivery valves 16, 16a, etc., of the dispensing system areshut down, liquid ow through the venturi 29 ceases and the pressure inthe bleed line 22 increases to such an extent that the pilot valve 35moves suiciently to cause the extension 61 to leave the bore 57 of theplug 47. As soon as this occurs the pressure in Vthe bleed line 22operates over a larger area comprising the area of the face A at the end61 and the area of the annular face E at the end of the enlarged end 6G,with the result that the pilot valve continues its movement againstspring 51 to uncover the whole area of the port 64, thereby admittingliquid far in excess of the rate of bleed through the bore 45 andapplying maximum pressure against the face D of the piston 39. The valve34 then opens fully and the non-return valve i4 closes with the resultthat the valve 12 provides a low-resistance bypass through which liquidcan be circulated by the pump 9 at a low pressure and with littleexpenditure of energyv by the engine driving the pump.

When liquid ow to a dispensing station recommences, the pressure in thebleed line 22 decreases and the pilot valve 35Y moves to the right underthe action of the spring 51. However, since in the extreme open positionof the pilot valve 35, the pressure of the liquid in the bleed line 22acts on the whole of the area of the faces A and E (on the portions 6iand 69 of the member), the pilot valve 35 will move to the closedposition only when the bleed line pressure falls to a value, for example15%, below that causing initial opening of the pilot valve 35. This hasthe etfect of compensating to a certain extent any pressure drop due toleakage in the delivery line 13 or the dispensing system, therebyavoiding chattering kor sudden reciprocatic-ns of the pilot valve.

During closure of the pilot valve liquid trapped in the enlarged portion53. of the chamber 33 by the re-entry of the extension 61 of the valvemember into the bore 57 ilows t'o suction via the bore 68 in the valveVmember and the port 63, and the port 64 becomes progressively obturatedby the valve member 35, thereby correspondingly reducing the pressureacting on the face D of the piston 39 which results in partial orcomplete closure of the valve member 3a.

The pressure storage vessel 23, which is an optional component, alsofunctions Vto retain in the delivery line 13 the pressure required tomaintain the pilot valve 35 open in spite of any moderately smallleakage that may occur in the delivery line 13 or inthe dispensingsystem itself over the period during which the delivery valves are shut.The pressure storage vessel 23 also acts as a shock absorber and maythus replace any shock pressure absorber which might otherwise beneeded.

It will be apparent from the foregoing description that the presentinvention comprises Va liquid dispensing system which includes meansoperative automatically in response to pressure variations in thedelivery line to provide the usual by-pass facility on partialVshut-down of the dispensing system and in addition to provide alowresistance by-pass for the pump on complete shut-down thereof,without the need for any control of the pump by the operator at thedispensing stations. Y

While the fluid in the transmission or bleed line 22 is, in theembodiments shown, the same as that owing through the delivery pipeline, it should be understood that the invention is not limited thereto,and that the fluid acting on the movable wall A of the pilot valve maybe a different liquid which may, if desired, be isolated from the liquidin the pipe line through any suitable means, such as a diaphragm orpistons,

i ciaim as my invention: v

l. A liquid-dispensing System including: a pump having suction anddischarge sides; a delivery pipe line connected to the discharge side'of said pump; at least one dispensing device including a delivery valveconnected to said delivery pipe line; a non-return valve in saiddelivery pipe line, said non-return valve being disposed to permitliquid ow from said pump to the ldispensing des vice but not vice versa;a by-pass line providing a low- Vresistance ow path for liquid betweenthe discharge and suction sides of said pump; a by-pass valve in saidbypass line which is operative to vary the resistance to liquid' flowthrough said by-pass line; and a pressure-responsive valve actuator forsaid by-pass valve connected to respond to the pressure in said deliverypipe line at a point therein located between said non-return valve andthe said delivery valve, said actuator being disposed to actuate theby-pass valve to decrease the said resistance to ow through the by-passline when the pressure at said point kin the delivery pipe line rises toa predetermined value.

2. A liquid-dispensing system as set forth in claim 1 wherein said valveactuator is arranged to increase Vthe said resistance to flow throughthe by-pass line only when the pressure at said point in the deliverypipe line falls to a second predetermined value Which is lower than saidbetween said non-return valve and the said delivery valve;

a by-pass line providing a low-resistance flow path for liquid betweenthe discharge and suction sides of said pump; a by-pass valve in saidby-pass line which is operative to vary the resistance to liquid flowthrough said bypass line; and a pressure-responsive valve actuator forsaid by-pass valve connected to respond to the pressure in said deliverypipe line at a point therein located between said non-return valve andthe said delivery valve, said actuator being disposed to actuate theby-pass valve to decrease the said resistance to ow through the by-pass`line when the pressure at said point in the delivery pipe line rises toa predetermined value.

4. A liquid-dispensing system including: a pump having suction anddischarge sides; a delivery pipe line connected to the discharge side ofsaid pump; at least one dispensing device including a delivery valveconnected to said delivery pipe line; a by-pass line providing alow-resistanceV ilow path for liquid between the discharge and suctionsides of said pump; a by-pass valve in said by-pass line including amain valve member movable to progressively di'erent positions to varythe said resistance to liquid flow in gradations to values dependentupon the positionV of the valve member; a pressure-responsive valveactuator l for said by-pass valve including at least one movable walloperatively connected to said main valve member for movement therewithand exposed to fluid pressure, a pilot valve having a pilot valve membermovable to progressively different positions and Varranged lto controlin gradations the admission of uid to act on swamps#- said'movable-wallin accordance'with the position 'of the pilotvalve member, said pilotvalve havingbiasing means for-biasing the pilot valve member to abiased'position anda second movable wall operatively connected to saidpilot'valve member for moving the pilot valve member progressively awayfrom said biased position' `upon the application of increasing fluidpressure against said second movable wall; and a uid pressuretransmission line Vhaving one end thereof connected to the pilot valvefor admittinga uid against said second movable wall and the other endthereof connected vto means for supplying fluid thereto at a pressurethat Vdepends upon the pressure in said delivery pipe line, saidrst-mentioned movable wall being so exposed to uid pressure as to'movesaid mainY valve member toward open position upon a rise in the said*pressure in the delivery pipe line.

5. A liquid-dispensing system as set forth in claim 4, wherein the saidmeans for supplying uid to the fluid transmission line includes meansresponsive both to the rate of liquid ow through said delivery pipe lineand to the static pressure therein, an increase in said static pressureacting in the same sense as a decrease in said rate of liquidfiow;

6. A liquid-dispensing system as set forth in claim 5, wherein therelation of the area of said second movable wall and the said biasingmeans is such that said main valve is moved to fully open position onlyupon substantially total cessation of ow in thesaid delivery pipe line.

7. A liquid-dispensingY system las setY forth in claim 4, whereinsaiddelivery pipe line has a non-return valve therein disposed to permit'liquid flow from said pump to the dispensing device but not vice versa,and said means for supplying uid to the uid pressure transmission lineis connected to a point in the delivery pipe line between saidnon-return valve and the said delivery valve and is disposed to supplyuid at a pressure determined by the pressure at said point in thedelivery pipe line.

8. A liquid-dispensing system as set forth in claim 7, wherein the saidmeans for supplying uid to the uid transmission line includes a venturiconstriction in said delivery pipe line and a port in said venturiconstriction connected to said transmission line, whereby the pressurein said transmission line becomes greater in response to an increase inthe said static pressure and also in response to a decrease in said rateof liquid ow.

9. A liquid-dispensing system as set forth in claim 8, wherein the saidliquid delivery pipe has at least two parallel branches at said pointtherein interconnected both at their upstream and downstream ends, saidventuri constriction being situated in the first of said branches andall the other of said branches containing dow-restrictive means fordiverting ow through the first said branch during low liquid flow rates,whereby at least some ow of liquid occurs through said venturiconstriction whenever any liquid flows through said delivery pipe line.

10. A liquid-dispensing system including: a pump having suction anddischarge sides; a delivery pipe line connected to the discharge side ofsaid pump; at least one dispensing device including a delivery Valveconnected to said delivery pipe line; a non-return valve in saiddelivery pipe line, said non-return valve being disposed to permitliquid ow from said pump to the dispensing device but not vice versa; aby-pass line providing a path having low-resistance to liquid flow fromthe discharge side to the suction side of said pump; a by-pass valve insaid by-pass line including a main valve member movable to differentpositions to control the said resistance to liquid flow to valuesdependent upon the position of the valve member; a pressure-responsiveactuator for said by-pass valve including at least one movable walloperatively connected to said main valve member for movement therewithand exposed to uid pressure, a pilot valve having a pilot valve membermovable to different positions and arranged to control the admission offluid to act on said movable wall in accordance with the position of thepilot valve member,

said plotvalve having biasing means-'for biasingthe pilot valve memberto a biased'position at which the admission of Vtluid is controlled soas tomove saidmain Valve member to impose a high resistance to flow'ofliquid in the bypass line and a second movable Wall operativelyconnected to said pilotl valve member for moving the pilot valveA memberaway from said biased position upon theappli-v cation of increasingfluid pressure against-said second' movable wall; and a uid pressuretransmission-line-hav-v ingone end thereof connected to the pilot valveto supply uld under pressure to act on said second movable wall and theother end thereof connectedV to a point in the liquid delivery pipe linebetween said non-return valve andthe" said deliveryvalve to receive uidat a pressure that rises with increasing pressure in said delivery pipeline.

ll. A liquid-dispensing system including: a pump having a suction sideconnected to a liquid supply source and a discharge side; a deliverypipe line connectedto the discharge side of said pump; at least onedispensing device including a delivery valve connected lto said deliverypipe line; a non-return valve in said delivery pipe line, saidnon-return valve being disposed to permit liquid ow from said pump tothe dispensing device but not vice versa;-a by-pass line providing alow-resistance'pathA for liquid flow -betweenthe discharge and suctionsides of said pump; a by-pass valve in said by-pass line which isoperative vtovarythe resistance toliquid lowv through said bypass line;a tuid .pressure-responsive valve actuator for said 'oy-pass valvedisposed to actuate the by-pass valve to decrease the said resistance tollow through the by-pass line when .the fluid pressure acting on theyactuator `in'- creases and to actuate the by-pass valve to increase thesaid resistance upon a decrease inthe said iluid pressure;A

and a uid transmission line having one end thereof connected to saidvalve actuator to admit said uid at a variable pressure so as to act onsaid actuator and having the other end thereof connected to saiddelivery pipe line at a point therein located between said non-returnvalve and said delivery valve in pressure-transmitting relation so as tosubject uid in the transmission line to a pressure that increases as thepressure in the delivery pipe line increases.

12. A liquid-dispensing system as set forth in claim l1, wherein thesaid delivery pipe line includes a venturi constriction at the saidpoint therein, in said venturi constriction having a port and thetransmission line being connected to the delivery pipe line through saidport, the said valve actuator being arranged to move the by-pass valveto fully open position only upon a rise in the pressure in thetransmission line to a predetermined value corresponding to a conditionof substantially zero flow of liquid through the venturi constriction.

13. A liquid-dispensing system as set forth in claim 12, wherein saidvalve actuator is arranged to move the bypass valve from its fully openposition only when the uid pressure in the transmission line falls to asecond predetermined value which is lower than said inst-mentionedpredetermined value.

l4. A liquid-dispensing system as set forth in claim 13 and including apressure storage vessel communicating with said delivery pipe line at apoint therein between said non-return valve and the said dispensingdevice.

l5. A liquid-dispensing device as set forth in claim ll, wherein thesaid by-pass valve and valve actuator include: a casing having a portedpartition dividing the casing into a high-pressure chamber and alow-pressure chamber connected by said by-pass line respectively to thedischarge side and to the suction side of said pump, said casing havingfurther a cylindrical chamber in open communication with thehigh-pressure chamber; a main valve member reciprovably mounted withinsaid casing and having a seating against said partition for closing theport therein, the area of said cylindrical chamber being greater thanthe area of said valve member; a piston in said cylindrical chamberconnected to said valve member, whereby pressure in said high-pressurechamber acts ammesse with a relatively larger force on said pistonurgingthe valve member to seat on the partition, and with a relativelysmaller'rforce on said valve member urging the valve member away fromthe partition; a passageway interconnecting the said high-pressurechamber and the end part of the cylindrical chamber on the side of thepiston remote from the high-pressure chamber; a pilot valve forregulating the flow of liquid through said passageway; and outletrneansfor the discharge of liquid from said end part of the cylindricalchamber.

16. A liquid-dispensing device as set Vforth in claim l5, wherein saidoutlet means for the cylindrical chamber includes a restricted duct forbleeding into said low-pressure chamber.

17. A liquid-dispensing device as set forth in claim l5, wherein saidpilot valve has a graduated passageway for regulating said flow ofliquid through the passageway in gradations in accordance with theposition of the pilot valve.

18. A valve actuator comprising a casing providing a Huid pressurechamber, said chamber containing therein at least one movable walladapted for operative connection to a valve member to be actuated; apilot valve having a pilot valve member movable to progressivelydifferent positions and arranged to control in gradations the admissionof iluid to act on said movable wall in accordance with the position ofthe pilot valve member, said pilot valve having biasing means forbiasing the pilot valve member to a biased position and a second movablewall operatively connected to said pilot valve member for moving thepilot valve member progressively away from said biased position upon theapplication of increasing uid pressure against said second movablewall;'and an inlet to said casing for admittinga pressure iiuid againstsaid second movable wall.

19; A valve-and a valve actuator therefor comprising: a casing'having aported ypartition dividing thercasing into a high-pressure chamber and alow-pressure chamber; openings'in said casing cormnunicating with saidchambers for connecting feed and discharge pipes to the high-pressureand low-pressure chambers, respectively,V

urging valve member totseat on the partition, and with a relativelysmaller force on said valve member'urging the valve member away from thepartition; a passageway interconnecting the said high-pressure chamberand the end part of the cylindrical chamber on the side of the pistonremote from the high-pressure chamber; a pilotV valve forV regulatingthe ow of liquid through said passageway; and outletmeans for thedischarge of liquid from said end part of the cylinder.

References Cited in the ile of this patent UNITED STATES PATENTS1,978,597 Peter oct. 30, 1934 2,138,755 Beesten Nov. 29, 1938 2,330,703Grise sept. 28, 1943

1. A LIQUID-DISPENSING SYSTEM INCLUDING: A PUMP HAVING SUCTION ANDDISCHARGE SIDES; A DELIVERY PIPE LINE CONNECTED TO THE DISCHARGE SIDE OFSAID PUMP; AT LEAST ONE DISPENSING DEVICE INCLUDING A DELIVERY VALVECONNECTED TO SAID DELIVERY PIPE LINE; A NON-RETURN VALVE IN SAIDDELIVERY PIPE LINE, SAID NON-RETURN VALVE BEING DISPOSED TO PERMITLIQUID FLOW FROM SAID PUMP TO THE DISPENSING DEVICE BUT NOT VICE VERSA;A BY-PASS LINE PROVIDING A LOWRESISTANCE FLOW PATH FOR LIQUID BETWEENTHE DISCHARGE AND SUCTION SIDES OF SAID PUMP; A BY-PASS VALVE IN SAIDBYPASS LINE WHICH IS OPERATIVE TO VARY THE RESISTANCE TO LIQUID FLOWTHROUGH SAID BY-PASS LINE; AND A PRESSURE-RESPONSIVE VALVE ACTUATOR FORSAID BY-PASS VALVE CONNECTED TO RESPOND TO THE PRESSURE IN SAID DELIVERYPIPE LINE AT A POINT THEREIN LOCATED BETWEEN SAID NON-RETURN VALVE ANDTHE SAID DELIVERY VALVE, SAID ACTUATOR BEING DISPOSED TO ACTUATE THEBY-PASS VALVE TO DECREASE THE SAID RESISTANCE TO FLOW THROUGH THEBY-PASS LINE WHEN THE PRESSURE AT SAID POINT IN THE DELIVERY PIPE LINERISES TO A PREDETERMINED VALUE.